Electrooptical system



March 2, 1937. GRAY 1 2,072,478

ELECTROOPTI GAL SYSTEM Filed June 28, 1930 INVENTOR FTC AV ow.

A T TORNEV Patented Mar. 2, 1937 UNITED STATES PATENT OFFICE ELECTROPTICAL SYSTEM 7 Frank Gray, New York, N. Y., assignor to Bell Telephone Laboratories,

Incorporated, New

This invention relates to electro-optical systems and more particularly to multi-channel television systems.

The prior art discloses electro-optical systems in which a field or object to be transmitted is completely illuminated, and mechanism is provided to scan the field so that light radiations reflected from separate strips of the field are caused to traverse two or more light sensitive devices, each included in a different communication channel.

It has also been proposed to simultaneously illuminate different strips or paths of a scene or object by a plurality of moving beams of light,

each of which comprises a different spectral band, and to use the light simultaneously reflected from the areas illuminated by the different light beams to respectively actuate light sensitive devices, each included in a different communicating channel.

The present invention provides a system in which the advantageous features of the above described disclosures are simultaneously utilized to effect multi-channel operation.

An object of the present invention is to effect simultaneous beam illumination and scanning of a field or subject, together with transmission over a plurality of channels.

One embodiment of the invention may include a light source and a scanning disc, provided with two or more sets of spirally arranged apertures for producing a plurality of moving beams of light for illuminating distinct strips of paths of the scene or object to be transmitted,

lenses for controlling the supply of light to the field or object and for gathering the light reflected from simultaneously illuminated areas to constitute separate beams which are applied to a portion of the scanning disc provided with prisms, which operate to direct the respective beams of reflected light to different light sensitive devices included in separate communication channels.

A more detailed description of the invention 45 follows and is illustrated in the attached draw- Fig. 1 illustrates a television transmitting apparatus, involving the invention;

Fig. 2 is a front view and Fig. 3 is a rear view 50 of a portion of the scanning disc of Fig. 1,

Fig. 4 is a section through the disc 3, and

Figs. 5 and 6 are front and side views, respectively, of a portion of a scanning disc with prisms contiguously mounted thereon.

55 The transmitter of Fig. 1 comprises a source of light I, a lens 2 for imaging the source I upon an intermediate portion of a rotating disc 3. The intermediate portion of the disc is provided with two rows of spirally arranged apertures 4 and .5.

Two beamsof light, projected through the apertures 4 and 5, are focused by the lens 6 upon the surface of the subject or field to be transmitted I; The light beam projected through the apertures 4 illuminates a series of unit bands 10 or strips of the field, for example the first, third, fifth, etc. Alternate adjacent unit bands or lines of the field, i. e. the second, fourth, sixth, etc., are illuminated by the beam projected through the apertures 5. The two series of apertures 15 are of such number and so arranged that, when the disc has completed a single revolution, the subject 1 has been completely illuminated.

As herein described, the mode of scanning the field of view or subject is the same as that dis- 20 closed in application Serial No. 227,649 filed October 21, 1927, by applicant.

Light reflected from the elemental areas, comprising the unit bands illuminated by the light beams supplied through the rows of apertures 4 and 5, respectively, are concentrated by the lens 8 upon a portionv of the rotating disc 3 adjacent its periphery.

The beam, constituting the light rays reflected from the elemental areas of the band illuminated 30 by the light supplied through the apertures 4, is focused upon a row of prisms 9, which directs it to a photoelectric cell ID.

The beam comprising the light rays reflected from elemental areas included in the band illuminated by the light passing through the aperture 5, is focused upon a row of prisms H,

by which it is directed to photoelectric cell [2.

The photoelectric cells I0 and I2 are thereby actuated to cause the production of two distinct 40 image currents which respectively vary as the tone values of the elemental areas of the alternate unit bands of the subject 1. Cells l0 and I2 are included in separate circuits l3 and I4, which may each include an amplifier IE to raise the image current wave to the desired power level.

The respective amplified image currents may be supplied to distinct transmission paths l1 and I 8, extending to a receiving station, or to modulators in which they are combined with carrier waves of different frequencies. The distinct image-current carrier modulated waves may be transmitted over separate channels of a carrier line or a radio system.

The sector of the scanning disc 3, shown in Fig. 2, clearly illustrates the relative positions of the rows of apertures 4 and 5 and the rows of prisms 9 and II.

Figs. 3 and 4 illustrate a segment of the disc 3 having the prisms 9 and II mounted thereon to effect selective application of the light, reflected from the elemental areas of the respective unit bands of the object, upon the photoelectric cells l and I2.

The mode of controlling the application of the beams of reflected light to the respective light sensitive devices is similar to that disclosed in Patent 1,989,618, of H. E. Ives issued Jan. 29, 1935.

Preferably the apertures 4 and 5 and prisms 9 and II, which occupy corresponding positions on the spirals, should be staggered with respect to each other as herein shown. However, they may be contiguous to each other or they may is suitable for the purpose of this invention, is

disclosed in the above mentioned Ives patent.

The receiving light sources may be of any well known type adapted to produce a small sized intense spot of light which varies in accordance with the exciting current. A glow lamp, suitable for this purpose, is disclosed in patent of H. W. Weinhart, issued July 18, 1933.

The present invention therefore provides a system in which distinct areas of the subject or field may be illuminated by moving beams of light of high intensity and may be scanned to produce separate image currents which are respectively transmitted over distinct communication chane nels. Hence it embodies the attendant advan: tages of beam scanning, as disclosed in the above mentioned application of Gray, and reduction in the frequency range used to transmit the subject or field of View.

What is claimed is:

1. A television system comprising a source of light, a plurality of photoelectric means, apertured means for simultaneously producing a plurality of beams of light which traverse different regions of the object, means for simultaneously focusing at different points light reflected from different illuminated regions on said object at any instant, a plurality of optical prisms, and means for successively moving groups of said prisms through said focal points respectively to direct said beams of light to different ones of said photoelectric means.

2. A television system comprising a source of light, a plurality of photoelectric means, apertured means for simultaneously producing a plurality of beams of light which traverse different regions of the object, means for simultaneously focusing at different points light reflected from different illuminated regions on said object at any instant,-a plurality of prisms carried by said apertured means which successively moves groups of said prisms through said focal points respectively'to'direct said beams of light to different ones of said photoelectric means.

3. Television transmitting apparatus comprising a scanning disc having a series of light openings, prismatic means at said openings for deflecting the light passing through one portion of each opening relative to that passing through another portion thereof, means for imaging adjacent unit areas of the transmitted view respectively on said portions and a plurality of photoelectric means arranged to receive the light respectively from said portions.

4. Television transmitting apparatus comprising ascanning disc having a series of elongated light openings, prisms at said openings for refracting the light passing through one portion of each opening relative to that passing through another portion thereof, means for imaging respectively on said portions adjacent unit areas of the view being transmitted, and a separate photoelectric device for receiving the light from each of said portions.

5. In television apparatus, a scanning disc having a series of light openings each comprising portions arranged radially with respect to each other, and a pair of prisms at each opening arranged to deflect the light passing one portion with respect to the light passing the other portion.

6. In television apparatus, a scanning disc having a series of light openings and a pair of prisms at each of said openings arranged radially with respect to each other, whereby all of the light passing said openings is refracted by one prism or the other.

FRANK GRAY. 

